1. Field of the Invention
The present invention relates to abrasion resistant ferro-based sintered alloy for use as abrasion resistant members of internal combustion engines, more particularly, those members which require high thermal resistance and high abrasion resistance simultaneously such as valve seats, valves, etc. and other slidable members for internal combustion engines.
2. Description of the Prior Art
Thermal and abrasion resistant sintered alloys for use as valve seats which can exhibit high abrasion resistance and thermal resistance and corrosion resistance even when leadless gasoline is used as a fuel are described in U.S. Pat. No. 3,827,863.
These materials comprise various elements introduced in large amounts in a form of alloy powder, powder mixture or single powder of the elements. The addition of the elements often causes a problem since these elements, in particular cobalt, are available only with difficulty.
Further, members to be used under the conditions of high temperatures and high loads tend to suffer various drawbacks, for example, lead will be fused and flow out when the alloy impregnated with lead is used, the hardness of those members subjected to steam treatment will be too high and the material will become brittle. In addition, productivity is decreased by the addition of production steps when such treatments are effected.
It is, therefore, strongly desired that alloy comprising as small as possible an amount of useful additive elements but exhibiting excellent thermal resistance, corrosion resistance and abrasion resistance simultaneously be developed to thereby save natural resources as well as improve productivity.